Furnaces, often used to heat households and buildings, generally burn a combustible fuel (e.g., natural gas) in a burner to produce hot combustion gasses, which, in turn, provide heat to a heat exchanger before the combustion gasses are exhausted outside the building. Commonly, the hot combustion gasses travel through one or more heat exchanger tubes, and a blower forces air across the heat exchanger tubes, thereby transferring heat from the hot combustion gasses to the air, the air then being distributed throughout the building via ductwork.